With the advent of fiber reinforced composite materials, it is necessary to analyze the mechanical behavior of the fibers used in the composites. Most techniques for testing single fibers or filaments at room temperature have involved either the direct gripping of fibers, the gripping of a tab attached to the fiber, or a combination thereof. Most techniques using a tab are based on a standard test method 337913 of the American Society for Testing and Materials. Some of these single filament test methods have been adapted for high temperature tests in air. Data from high temperature tests is useful for understanding fiber behavior in air under oxidizing conditions encountered during composite use. Unfortunately, the fibers may encounter much different environments during fabrication and use if they react with a matrix or undergo internal chemical reactions which evolve gaseous species. Under these conditions, it is desirable to test the fibers in the environment to which they are expected to be exposed.
Current evaluations of the mechanical behavior of fibers which include tensile strength, elastic modulus, stress-rupture and creep-rupture under non-ambient conditions have been performed by two types of methods. The first, heat treatment methods, have involved exposure of the fiber to heat in a controlled environment or vacuum, and then subsequently removing and testing the fiber at room temperature. Such methods only simulate in situ fiber behavior. The second, high temperature methods, actually test the fiber at an elevated temperature, but not in a controlled environment. There have been few analyses of the mechanical behavior of fibers at elevated temperature under an explicitly controlled environment due to the complexity of controlling the environment around the fiber during heating.
It is an objective of this invention to provide an apparatus for testing one or more fibers in a controlled environment. It is a further objective to provide an apparatus with improved measuring capabilites in a controlled environment.